Quantitative and qualitative analysis of retinoids in Artemia and copepods by HPLC and diode array detection

Different concentrations of retinoids have been reported in Artemia. The levels vary from 0-362 μg g−1Artemia (dry wt.). The aim of this study was to investigate the actual retinoid concentration in Artemia and compare it with levels in copepods. Samples of both DC-DHA Selco (INVE, Ghent, Belgium) from the bottle and after 12 h in the enrichment tank in addition to enriched and unenriched Artemia and copepods from a pond system were collected and analysed for vitamin A components. The analyses were conducted using two different HPLC (high pressure liquid chromatography) methods to ensure the justness of the results. The DC-DHA Selco contained 132.7 μg vitamin A g−1. After 12 h in the enrichment tank we could not detect any vitamin A. None of the following retinoids were observed in Artemia or copepods with any of the methods: all-trans-retinol (at-ROH), 9-cis-ROH or at-3,4-didehydro-ROH (at-3,4-dd-ROH). Method 2 detects several other retinoids when present, but none of the following were found in the two live prey organisms: cis or trans 3,4-dd-RA, cis or trans 3,4-dd-ROH, cis or trans 3,4-dd-RAL, cis or trans ROH or cis or trans RA. This implies that larvae feeding on either copepods or Artemia must meet their retinoid requirement from other sources than retinoids.